JPH0429401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to fine particles which have an extremely wide range of applications such as performance testing of clean rooms and microporous filters, coating materials for magnetic tapes and heat exchanger walls, and fuel catalysts. The present invention relates to a device for generating particles having arbitrary particle size in the field of.

Conventional technology Fine particles and ultrafine particles (several tens of angstroms ~
100μm) generation and adjustment methods, various research and development efforts are underway; for example, in March 1985,
On April 10th, Volume 5 of the Technology Forecast Series, New Materials Edition, published by Japan Business Report Co., Ltd., included papers titled ``Current Status and Future Prospects of Ultrafine Particles'' and ``Prospects of Fine Ceramics.'' As described in this publication, the conventional method for preparing fine particles involves introducing a carrier gas such as N ₂ , He, Ar, H _{2 ,} etc. into a mixer containing a liquid containing fine particles at a certain concentration. Fine particles are dispersed by bubbling gas inside. However, with this method, the variation in particle size of the fine particles produced becomes extremely large, and furthermore, it is impossible to generate a quantitatively stable number of particles. This has resulted in various drawbacks due to variations in particle size and number of particles.

Problems to be Solved by the Invention An object of the present invention is to provide an apparatus that can stably generate particles having any particle size in the air for a long period of time.

Another object of the present invention is to provide an apparatus that can stably generate a large number of particles over a long period of time.

Means for Solving the Problems and Their Effects The above objects of the present invention are to provide an ultrasonic transducer attached to a part of a liquid tank containing a liquid to be atomized and a substance capable of forming particles; a first air outlet provided at the top of the liquid tank for sending gas, a blowing pipe extending upward from the top of the liquid tank, a second blowing port provided in the middle of the blowing pipe for sending gas, and a first air blowing port. This is achieved by a generator for generating particles of arbitrary particle size, which includes a first valve mechanism that adjusts the amount of air blown from the opening, and a second valve mechanism that adjusts the amount of air blown from the second air outlet.

That is, the present invention utilizes an ultrasonic atomization device.
By changing the distribution of the amount of gas sent into the ultrasonic atomizer from the first air outlet and the amount of gas sent from the second air outlet towards the middle of the blowout pipe, It is possible to generate particles with a stable particle size and quantitatively stable particles in the air. Furthermore, by changing the liquid concentration as necessary, it becomes possible to generate particles of arbitrary particle size and number.

That is, by controlling the first valve mechanism to adjust the amount of air sent into the liquid tank from the first air outlet, it is possible to control the diameter of the particles carried from the liquid tank to the blowout pipe. . because,
The particle size of the mist generated from the liquid surface varies to some extent, but larger particles have a higher settling speed, so below a certain air volume, the mist falls to the liquid surface without being carried to the blowout pipe. This makes it possible to suppress the diameter of particles heading toward the blowout pipe to a certain level or less. Furthermore, by controlling the second valve mechanism to adjust the amount of air flowing from the second air outlet to the outlet, it is possible to control the mixing ratio of air and mist at the outlet, that is, the particle concentration. Furthermore, by changing the concentration of the solution in the liquid tank, it is also possible to control the particle size of the mist generated from the liquid surface after drying.

The reason why we are able to obtain a stable particle size is because fine particles, polymer materials, chlorides, etc. are uniformly distributed or dissolved in the liquid at a certain concentration. When the mist is carried into the air, only the solvent (solvent) evaporates, and the amount of fine particles, polymer materials, chlorides, etc. that aggregate in the air is uniform. Therefore, it is thought that the particle size of the generated particles becomes uniform.

Although various gases other than air can be used as the gas sent through the ventilation ports, it is preferable that each ventilation port uses dry gas without moisture.

The invention will now be further explained with reference to embodiments of the accompanying drawings.

Embodiment FIG. 1 represents a preferred embodiment of the particle generator according to the invention, in which water is placed as a solvent in the liquid tank 10 as the liquid to be atomized and as a substance capable of forming the particles to be atomized. Latex balls with a particle size of 0.091 μm are mixed. A thick electric vibrator 12 is attached to the bottom of the liquid tank 10 as an ultrasonic vibrator, and receives an AC signal from a drive circuit 14 and vibrates to generate ultrasonic vibrations, thereby vibrating the liquid and removing water and latex from the surface. It is designed to scatter the balls in a mist. A first air outlet 16 for feeding dry air is provided on the upper side wall of the liquid tank 10, and a blowing pipe 20 extending upward is attached to the upper surface of the liquid tank 10. Further, a second blowing port 18 for feeding dry air is provided in the middle of the blowing pipe 20, and the blowing pipe 20 extends horizontally from this position and releases latex particles aggregated to a predetermined particle size from an outlet 22. I'm starting to do that. Dry air is supplied to the ventilation ports 16 and 18 from an air pump 24 via valves 26 and 28, respectively. The valves 26 and 28 are controlled by a control mechanism 30;
For example, the flow rate is adjusted in response to a signal from an electric, electronic, or pneumatic automatic control device, and the amount of air supplied to the first and second ventilation ports is adjusted to change the distribution ratio.

FIG. 2 is a principle diagram illustrating the fact that the particles generated by the apparatus shown in FIG. 1 have a uniform particle size. First, in state A, latex spheres are uniformly dispersed in an aqueous solution. In state B, latex spheres are included in the mist generated from the water surface by ultrasonic vibration. In state C, only the solution in the mist, that is, water, is evaporated by the drying gas, leaving latex spheres aggregated to a particle size of X. In state D, only latex spheres coagulated to particle size X remain, and the water completely evaporates and becomes invisible. In this way, particles (fine particle aggregate) with uniform particle sizes are discharged from the outlet.

Experimental Example Figure 3 shows the number of particles generated (particle size
0.091 μm} is measured and its change over time is determined. The concentration of generated particles on the vertical axis is expressed in the number per cubic foot (0.0283 cubic meter) on a logarithmic scale. From this graph, it was found that the concentration of generated particles was almost uniform over 3 hours, and extremely stable particle generation was obtained.

Figure 4 shows that particles are generated by the method of the present invention using an aqueous solution of NaCl dissolved in water instead of latex spheres, and the NaCl concentration is varied between 0.1% and 1% while keeping the air volume distribution constant. This is a graph showing the relationship between the number of particles generated and the particle size. In this graph, the particle size peak is clearly visible, demonstrating that particles of approximately uniform size can be obtained. Also
It was also found that any particle size could be obtained by changing the concentration of NaCl.

In the above Examples and Experimental Examples, the case where the solvent (solvent) is water is described, but the solvent is not limited to water, and may be used depending on the type of solute, such as alcohol, ether, petroleum ether, benzene, ethyl acetate, chloroform, etc. can be used.

Effects of the Invention As explained in detail above, according to the apparatus of the present invention, particles with any particle size can be stably generated in the air for a long time, and the number of particles can also be stabilized for a long time. Its effects are extremely remarkable, such as enabling more accurate performance testing of clean rooms and microporous filters, as well as improving the performance of magnetic tapes and heat exchangers.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a particle generator according to the present invention, FIG. 2 is a schematic diagram showing the principle of the present invention, and FIG.
The figure is a graph showing the change in the number of generated particles over time.
The figure is a graph showing the relationship between the number of particles generated and the particle size by varying the concentration of the solution. 10...Liquid tank, 12...Ultrasonic vibrator, 14...
...Drive circuit, 16, 18...Blower port, 20...Blowout pipe, 22...Outlet, 24...Pump, 2
6,28...Valve.

Claims (1)

[Claims] 1. An ultrasonic vibrator attached to a part of a liquid tank containing a liquid to be atomized and a substance capable of forming particles, and a first air blower installed above the liquid tank to send gas. an outlet, a blowout pipe extending upward from the top of the liquid tank, a second blowout port provided in the middle of the blowout tube to send gas, and a first valve that adjusts the amount of air blown from the first blowout port. 1. A generator for generating particles of any particle size, comprising: a mechanism; and a second valve mechanism that adjusts the amount of air blown from a second air outlet. 2. The device according to claim 1, wherein the gas sent from each of the air outlets is dry air without moisture.